Similarities and Differences in the Immune Characteristics of Intestinal Gamma Delta T Cells From Patients With Crohn's Disease and Ulcerative Colitis and Their Correlation With Disease Activity.

BACKGROUND: Intestinal γδ T-cell immune characteristics and their relationship with disease activity in Crohn's disease (CD) and ulcerative colitis (UC) remain to be fully clarified. METHODS: Biopsies from 21 CD, 21 UC and 21 healthy controls were analyzed by flow cytometry for γδ T-cell frequency, cytotoxicity (perforin, granzyme-B), activation (HLA-DR) and exhaustion (PD-1). ROC curves were used to evaluate the diagnostic performance of these indices. Vγ subsets were profiled using published scRNA-seq data. RESULTS: As disease activity increased, intestinal γδ T cells in CD and UC patients decreased and could not activate. The differences were that the cytotoxicity of intestinal γδ T cells in CD patients was always normal as disease activity increased. In contrast, the cytotoxicity of intestinal γδ T cells in UC patients was suppressed. Different Vγ subsets in CD or UC patients showed different immune characteristics, which might lead to different immune characteristics of γδT cells in CD or UC patients at different disease active stages. Furthermore, γδ T cell and HLA-DR+ γδ T cell ratio were good indicators in diagnosing CD. The ratios of γδ T cell, HLA-DR+ γδ T cell, PD-1+ γδ T cell, and Perforin+ γδ T cell exhibited values for diagnosing UC. PD-1+ γδ T cell ratio was a valuable indicator to help distinguish CD from UC. CONCLUSION: Intestinal γδ T cells exhibit both shared and divergent features in CD and UC that closely parallel disease activity, supporting their potential as immune biomarkers for diagnosis and discrimination between the two diseases.